Although, Common Ads can be removed from Firefox Using AdBlock Extension, there's nothing availble to actually remove those Google Text Framed Ads we see, you can always Right click and Block, but that's a temporary solution, here's How you can Get rid of those ads for once and for all!
Tools You Need:
Mozilla Firefox Browser
ChromeEdit Extension For Firefox
Download and Install ChromEdit, which let's you Edit User Files, Restart Firefox, and Open ChromEdit
Go to userContent.css and add the following Code:
Code:
/* Block Ads v.2004-06-12 by Neil Jenkins 
   Portions of this ruleset are derived from the ad blocking css by Joe Francis at: 
   http://www.floppymoose.com/ 
   Some code also contributed by Mike Hokenson: 
   http://www.gozer.org/mozilla/ad_blocking 
*/ 

iframe[width="120"][height="600"], a img[width="120"][height="600"], 
iframe[width="125"][height="600"], a img[width="125"][height="600"], 
iframe[width="150"][height="100"], a img[width="150"][height="100"], 
iframe[width="150"][height="600"], a img[width="150"][height="600"], 
iframe[width="160"][height="600"], a img[width="160"][height="600"], 
iframe[width="300"][height="250"], a img[width="300"][height="250"], 
iframe[width="336"][height="280"], a img[width="336"][height="280"], 
iframe[width="468"][height="60"],  a img[width="468"][height="60"], 
iframe[width="470"][height="62"],  a img[width="470"][height="62"], 
iframe[width="728"][height="90"],  a img[width="728"][height="90"], 
iframe[width="730"][height="92"],  a img[width="730"][height="92"], 
iframe[width="600"][height="120"], object[width="125"][height="300"], 
iframe[width="180"][height="150"], 
iframe[src*="/ad-"], 
iframe[src*="/ad."], 
iframe[src*="/ad/"], 
iframe[src*="/ad_"], 
iframe[src*="/adframe"], 
iframe[src*="/ads"], 
iframe[src*="/adv"], 
iframe[src*="/adx"], 
iframe[src*=".ad"], 
iframe[src*="_Banner"], 
iframe[src*="BET365"], 
iframe[src*="/click"], 
iframe[src*="?click"], 
iframe[src*="googlesyndication"], 
iframe[src*="promos"], 
iframe[name="bsadframe"], 
iframe[id="adFrame"], 
iframe[id="splashFrame"], 
img[src*="/ad-"], 
img[src*="/ad."], 
img[src*="/ad/"], 
img[src*="/ad_"], 
img[src*="/ads"], 
img[src*="/adv"], 
img[src*="/adx"], 
img[src*=".ad"], 
img[src*="_ad_"], 
img[src*="/click"], 
img[src*="?click"], 
img[src*="Editorial_Promos"], 
img[src*="/toms_skyscraper_"], 
img[src$="images/logos/amazon_international.gif"], 
img[src*="freshmeat.net/button.gif"], 
img[src*="pic.geocities.com/images/"], 
img[src*="i.imdb.com/Vpics/"], 
img[src*="i.imdb.com/Photos/CMSIcons"], 
img[src*="i.imdb.com/Icons/apix/"], 
img[src*="i.imdb.com/Icons/kpix/"], 
img[src*="i.imdb.com/apix/"], 
img[src*="sportsbybrooks.com/farkbutton.gif"], 
img[alt*="advert"], 
img[alt*="Click Here To Visit Our Sponsor"], 
img[alt*="Sponsored Links"], 
img[name="fixedSpImg"], 
a:link[href*="/ad-"] img, 
a:link[href*="/ad."] img, 
a:link[href*="/ad/"] img, 
a:link[href*="/ad_"] img, 
a:link[href*="/ads"] img, 
a:link[href*="/adv"] img, 
a:link[href*="/adx"] img, 
a:link[href*=".ad"] img, 
a:link[href*="/banner"] img, 
a:link[href*="/click.cgi"] img, 
a:link[href*="/clickcgi?"] img, 
a:link[href*="/clickover"] img, 
a:link[href*="/clickthr"] img, 
a:link[href*="/click-"] img, 
a:link[href*="=click"] img, 
a:link[href*="?click"] img, 
a:link[href*="/A="] img, 
table table table[width="346"][height="280"], 
table[class="metatable"], 
table[id="RefAd"], 
table[cellspacing="0"][width="160"][height="329"][bgcolor="#000000"], 
table[cellpadding="5"][width="150"][style="border: 1px dashed rgb(221, 170, 170); background-color: rgb(236, 248, 255);"], 
table[border="0"][height="600"][width="120"], 
table[height="90"][cellspacing="0"][cellpadding="0"][width="728"][border="0"], 
table[border="0"][cellpadding="3"][cellspacing="0"][height="40"][width="100%"], 
table[border="0"][cellpadding="0"][cellspacing="4"][align="right"][width="20%"], 
table[border="2"] td[valign="top"][bgcolor="#ffffff"] table[width="138"], 
table[border="0"][cellpadding="1"][cellspacing="0"][width="626"][bgcolor="#6699cc"], 
table[bordercolor="red"][height="225"][cellspacing="0"][cellpadding="0"][width="190"][bgcolor="white"][border="0"], 
table[width="336"][border="0"][cellspacing="0"][cellpadding="0"][align="right"][style="margin-left: 10px; margin-bottom: 10px;"], 
table[width="770"][border="0"] tr[valign="top"] 
td[width="160"], 
td[class="cnnNavAd"], 
td[class="RHBarBody"], 
td[class="sl-table"], 
td[style="border-bottom: 1px solid rgb(204, 204, 204); padding: 7px 3px; background-color: rgb(255, 254, 249);"], 
td span[class="aoltextad"], 
form[name="frmLargeForm"], 
form[action*="click_lx.cgi"], 
form[action^="http://rd.yahoo.com/"], 
form[action=""][name$="SoapCity"], 
form[action=""][name^="728x90"], 
form[action=""][name^="300x250"], 
form[method="get"][action*="martindale"][name="MDH"], 
embed[type="application/x-shockwave-flash"][src*="_Banner"], 
embed[type="application/x-shockwave-flash"][src*="/ad"], 
embed[type="application/x-shockwave-flash"][href*="/ad"], 
embed[type="application/x-shockwave-flash"][src*=".ad"], 
embed[type="application/x-shockwave-flash"][href*=".ad"], 
embed[type="application/x-shockwave-flash"][src*="?click"], 
embed[type="application/x-shockwave-flash"][href*="?click"], 
embed[type="application/x-shockwave-flash"][src*="/click"], 
embed[type="application/x-shockwave-flash"][href*="/click"], 
embed[type="application/x-shockwave-flash"][href*="promos"], 
embed[type="application/x-shockwave-flash"][href*="=click"], 
embed[type="application/x-shockwave-flash"][href*="redirect"], 
embed[type="application/x-shockwave-flash"][href*="/A="], 
embed[type="application/x-shockwave-flash"][name*="advert"], 
embed[type="application/x-shockwave-flash"][name*="banner"], 
embed[type="application/x-shockwave-flash"][width="728"][height="90"], 
embed[type="application/x-shockwave-flash"][width="468"][height="60"], 
embed[type="application/x-shockwave-flash"][width="467"][height="63"], 
div[id="adstrip"], 
div[id*="advert"], 
div[id="dropin"], 
div[id="dwindow"], 
div[id="dcv_EchangeLay"], 
div[id="mntl"], 
div[id*="popup"], 
div[id="quack"], 
div[id="splashLayer"], 
div[id*="sponsor"], 
div[id="yschsec"], 
div[class="ovt"], 
div#contextualLinks, 
div[style="border: 1px solid rgb(221, 221, 221); padding: 5px; background-color: rgb(255, 255, 255);"], 
object[id="widgeth"], 
*[class="ad"], 
*[class*="eSext"], 
*[name*="klipad"], 
*[style*="/ads/"], 
*[id*="popover_"], 
*[src*="120x80"], 
*[src*="140x"], 
*[src*="?ad"], 
*[src*="-ad-"], 
*[src*="/adimage"], 
*[src*="/adimg"], 
*[src*="advert"], 
*[src*="=click"], 
*[src*="banners."], 
*[src*="banner_ads"], 
*[src*="/images/dinkus/more-arrow-lo.gif"], 
*[src*="/javaImages/ec/"], 
*[src*="/offer"], 
*[src*="/puffboxes/"], 
*[src*="/sponsors/"], 
*[src*="_sponsor_"], 
*[src*="/us.yimg.com/a/ya"], 
*[src*=".adbutler.de"], 
*[src*=".nedstatbasic.net"], 
*[src*=".tradedoubler.com"], 
*[src*=".travelocity./Sponsor_gifs/"], 
*[src*="a.consumer.net"], 
*[src*="bannermania.nom.pl"], 
*[src*="cash4banner.com"], 
*[src*="crazypopups.com"], 
*[src*="hit-now.com"], 
*[src*="hitbox.com"], 
*[src*="img.thebugs.ws"], 
*[src*="kinghost.com/ban/"], 
*[src*="klipmart"], 
*[src*="popupad.net/ats/"], 
*[src*="public"][src*="ad"], 
*[src*="/publicidad/"], 
*[src*="qkimg.net"], 
*[src*="qksrv.net"], 
*[src*="rcm-images.amazon.com"], 
*[src*="rcm.amazon.com"], 
*[src*="salon.com/Creatives"], 
*[src*="sexcounter."], 
*[src*="sideads/"], 
*[src*="statse.webtrendslive.com"], 
*[href*="logging.to"], 
*[href*="/referral/"], 
*[href*="tryaol"], 
*[href*="websponsors"], 
*[src*="banman.asp"], 
*[href*="banman.asp"], 
*[src*="bannerman"], 
*[href*="bannerman"], 
*[src*="?banner"], 
*[href*="?banner"], 
*[src*="/banner/"], 
*[href*="/banner/"], 
*[src*="/jump/"], 
*[href*="/jump/"], 
*[src*="adfarm"], 
*[href*="adfarm"], 
*[src*="advertising.com"], 
*[href*="advertising.com"], 
*[src*="ar.atwola.com"], 
*[href*="ar.atwola.com"], 
*[src*="atdmt.com"], 
*[href*="atdmt.com"], 
*[src*="bluestreak.com"], 
*[href*="bluestreak.com"], 
*[src*="clickxchange.com"], 
*[href*="clickxchange.com"], 
*[src*="doubleclick"], 
*[href*="doubleclick"], 
*[src*="falkag.net"], 
*[href*="falkag.net"], 
*[src*="fastclick.com"], 
*[href*="fastclick.com"], 
*[src*="mediaplex"], 
*[href*="mediaplex"], 
*[src*="netdirect.nl"], 
*[href*="netdirect.nl"], 
*[src*="spinbox."], 
*[href*="spinbox."], 
*[src*="tradedoubler.com"], 
*[href*="tradedoubler.com"], 
*[src*="transfer.go"], 
*[href*="transfer.go"], 
*[src*=".tribalfusion"], 
*[href*=".tribalfusion"], 
*[src*="valueclick"], 
*[href*="valueclick"], 
*[src*="http://216.92.211.171/"], 
*[href*="http://216.92.211.171/"], 
*[src*="http://216.92.21.16/"], 
*[href*="http://216.92.21.16/"] { 
        display: none !important; 
} 

img[src*=".advance"], 
img[src*="/click_"], 
img[src*="/cnn/images/clickability/"], 
img[src*="/logo2.m"], 
img[src$="/banners/com000.jpg"], 
a:link[href*=".add"] img, 
a:link[href*="admin"] img, 
a:link[href*="adobe"] img, 
a:link[href*=".adp"] img, 
a:link[href*="/advance"] img, 
a:link[href*="click.mp3"] img, 
a:link[href*="/imgres?imgurl="] img, 
a:link[href*=":head"] img, 
a:link[href*="http://nettracker."] img, 
embed[type="application/x-shockwave-flash"][src*="gallery"] { 
        display: inline !important; 
} 
#rh table[class=”metatable”]{display: none !important;} 
#rh div[class=”c”] {display: none !important;}
it's Really worth it considering, the page layout gets much cleaner after the hack.
PS: It removes Framed Yahoo! Ads as well, but not the Sidebar ons on Geocities Website.